RESUMEN
Mezcal is an alcoholic beverage obtained from the distillation of fermented juices of cooked Agave spp. plant stalks (agave must), and each region in Mexico with denomination of origin uses defined Agave species to prepare mezcal with unique organoleptic characteristics. During fermentation to produce mezcal in the state of Tamaulipas, not only alcohol-producing yeasts are involved, but also a lactic acid bacterial community that has not been characterized yet. In order to address this lack of knowledge on this traditional Mexican beverage, we performed a DGGE-16S rRNA analysis of the lactic acid bacterial diversity and metabolite accumulation during the fermentation of a typical agave must that is rustically produced in San Carlos County (Tamaulipas, Mexico). The analysis of metabolite production indicated a short but important malolactic fermentation stage not previously described for mezcal. The denaturing gradient gel electrophoresis (DGGE) analysis of the 16S rRNA genes showed a distinctive lactic acid bacterial community composed mainly of Pediococcus parvulus, Lactobacillus brevis, Lactobacillus composti, Lactobacillus parabuchneri, and Lactobacillus plantarum. Some atypical genera such as Weissella and Bacillus were also found in the residual must. Our results suggest that the lactic acid bacteria could strongly be implicated in the organoleptic attributes of this traditional Mexican distilled beverage.
Asunto(s)
Agave/microbiología , Bebidas Alcohólicas/microbiología , Bacillus/aislamiento & purificación , Ácido Láctico/metabolismo , Lactobacillales/aislamiento & purificación , Bacillus/clasificación , Bacillus/genética , Bacillus/metabolismo , Secuencia de Bases , Dermatoglifia del ADN , ADN Ribosómico/análisis , Electroforesis en Gel de Gradiente Desnaturalizante , Fermentación , Microbiología de Alimentos , Lactobacillales/clasificación , Lactobacillales/genética , Lactobacillales/metabolismo , Lactobacillus/clasificación , Lactobacillus/genética , Lactobacillus/aislamiento & purificación , Lactobacillus/metabolismo , Levilactobacillus brevis/clasificación , Levilactobacillus brevis/genética , Levilactobacillus brevis/aislamiento & purificación , Levilactobacillus brevis/metabolismo , Lactobacillus plantarum/clasificación , Lactobacillus plantarum/genética , Lactobacillus plantarum/aislamiento & purificación , Lactobacillus plantarum/metabolismo , México , Pediococcus/clasificación , Pediococcus/genética , Pediococcus/aislamiento & purificación , Pediococcus/metabolismo , Filogenia , Reacción en Cadena de la Polimerasa , ARN Bacteriano/genética , ARN Ribosómico 16S/análisis , Weissella/clasificación , Weissella/genética , Weissella/aislamiento & purificación , Weissella/metabolismoRESUMEN
Native strains of Trichoderma isolated from sorghum and common bean crop soils were investigated to assess their biocontrol potential over the phytopathogenic fungus Macrophomina phaseolina, isolated from diseased plants. The Trichoderma strains were characterized with a polyphasic approach, which combined the analysis of their morphological characteristics, enzymatic activity, macro- and microculture test results, rDNA restriction patterns (AFLP), ITS1-5.8S-ITS2 rDNA sequences, and protein profiles. The integration of these data sets can be used to select new isolates as biological control agents against native fungal phytopathogens. In general, we observed a positive correlation between the secretion of beta-1,3-glucanase and N-acetylhexosaminidase, and the biocontrol capacities of all the Trichoderma isolates. Strains with the best hyperparasitic behavior against M. phaseolina isolated from diseased bean and sorghum were Trichoderma sp. (TCBG-2) and Trichoderma koningiopsis (TCBG-8), respectively.